Fire Extinguisher Types & Use Cases
Fire Classifications & Corresponding Extinguishers
Fires are categorized based on the nature of the combustible materials involved. Recognizing the class of fire is the first step in selecting the correct extinguisher.
Class A Fires – Ordinary Combustibles (Solids)
Common Fuels: Wood, paper, cloth, rubber, plastics, and other organic materials.
Characteristics: Class A fires are the most common and typically involve solid, dry materials that burn and leave ash. These fires spread quickly, especially in environments with high airflow or stacked combustible materials.
Best Extinguishing Methods:
Water Extinguishers cool the burning material and help prevent re-ignition.
Water Mist Extinguishers smother the fire and create a barrier between the fuel and oxygen.
Dry Chemical Extinguishers can also be effective by interrupting the combustion process.
Safety Considerations:
Never use CO₂ or Class K Extinguishers, as they are ineffective on Class A fires.
Fire embers can reignite if not completely extinguished, so dousing with water or using an extinguisher rated for Class A is essential.
Class B Fires – Flammable Liquids & Gases
Common Fuels: Gasoline, diesel, oils, alcohols, propane, butane, and oil-based paints.
Characteristics: Class B fires do not leave embers or solid ash, but they can be extremely dangerous due to their ability to spread rapidly, particularly when fuel is spilled. Vapours from flammable liquids can ignite explosively if mixed with air.
Best Extinguishing Methods:
Carbon Dioxide (CO₂) Extinguishers displace oxygen, suffocating the fire without leaving residue.
Dry Chemical Extinguishers disrupt the chemical reaction, making them effective for liquid fires.
Safety Considerations:
Never use Water Extinguishers, as water can cause the fire to spread by splashing the liquid fuel.
In enclosed spaces, CO₂ Extinguishers should be used with caution as they displace oxygen.
Class C Fires – Electrical Fires
Common Fuels: Energized electrical equipment, wiring, circuit breakers, appliances, and power tools.
Characteristics: Class C fires occur when electrical faults cause overheating or sparks. Since electricity itself is not a fuel, Class C fires involve burning insulation, plastic casings, and wiring. The main hazard is electrocution if water or conductive extinguishing agents are used.
Best Extinguishing Methods:
Carbon Dioxide (CO₂) Extinguishers smother flames and do not leave residue, making them ideal for sensitive electronics.
Dry Chemical Extinguishers interrupt the fire’s chemical reaction while being non-conductive.
Water Mist Extinguishers (using de-ionized water) can cool and suppress electrical fires without conducting electricity.
Safety Considerations:
Always turn off the power source if possible before extinguishing an electrical fire.
Never use water-based extinguishers, as they can conduct electricity and cause serious injury.
Class C fires become Class A fires once power is shut off, so a secondary fire suppression method may be needed.
Class D Fires – Combustible Metals
Common Fuels: Magnesium, titanium, sodium, potassium, lithium, and aluminum dust.
Characteristics: Class D fires occur in industrial settings where reactive metals are processed or stored. These fires burn at extremely high temperatures and react violently with water and many common fire suppression agents.
Best Extinguishing Methods:
Specialized Dry Powder Extinguishers are the only safe method, as they absorb heat and smother the flames.
Metal fires may require specific extinguishing agents based on the metal type (e.g., sodium chloride for sodium fires, graphite powder for magnesium fires).
Safety Considerations:
Never use Water, Water Mist, or CO₂ Extinguishers, as these can cause explosive reactions or accelerate combustion.
Class D fires may relight if disturbed, so after extinguishing, the area should remain undisturbed until cooled completely.
Workers handling combustible metals should have immediate access to the correct extinguishers.
Class K Fires – Cooking Media & Greases
Common Fuels: Vegetable oils, animal fats, and deep-frying grease in commercial kitchens.
Characteristics: Class K fires burn at very high temperatures, often exceeding 700°F (370°C). These fires can reignite easily if not fully cooled. Water and common extinguishing agents are ineffective because burning oils repel water and can splash, spreading the fire.
Best Extinguishing Methods:
Wet Chemical Extinguishers release a special potassium-based solution that cools the fire and forms a foam barrier to prevent re-ignition.
Safety Considerations:
Never use water—it will cause the fire to explode or spread rapidly.
Class K fires are most common in commercial kitchens, making routine inspections of fire suppression systems essential.
Fire suppression systems built into commercial cooking equipment should be maintained and inspected regularly.
Final Thoughts: Fire Safety Starts with Awareness
Each fire class presents unique challenges, making it essential to choose the right extinguishing method. Using the wrong extinguisher can worsen the situation, increase the risk of injury, or even cause explosions. Regular fire safety training, inspections, and proper equipment placement are critical to ensuring safety in homes, businesses, and industrial facilities.
For expert fire suppression services, inspections, and maintenance, contact Kitchens & Extinguishers. Our team is dedicated to providing the best fire protection solutions tailored to your needs.